An Organic Light-Emitting Diode (OLED) has been applied to displays with a high performance more and more because of its advantages such as a high luminance, a wide viewing angle, a rapid response speed and etc. Traditional passive matrix OLED (PMOLED) requires shorter driving time for a single pixel as its display size becomes bigger, therefore an instantaneous current is increased and a power consumption is also increased. Further, an application with a big current would cause a voltage drop on an ITO line too great and an operation voltage at the OLED too high, which may decrease its efficiency in turn. As compared, an active matrix OLED (AMOLED) may solve these problem well by scanning input OLED currents progressively with switching transistors.
For an AMOLED (Active Matrix Organic Light Emitting Diode) display, not only a row strobing signal for controlling an ON/OFF state of a pixel connected with a gate is required to be generated, but also an ON/OFF state of the organic light emitting diode (OLED) is required to be controlled. A state controlling signal for the OLED is a positive level signal with respect to an AMOLED display backboard composed of p-type transistors, in order to ensure that an OLED device is in the OFF state during a process for writing display data into pixel cells and the OLED device is turned on to emit light after the display data is written into the pixel cells, thereby a display image is guaranteed not to generate flickers due to an unstable state of a pixel circuit as the data is written.